Announcement

Collapse
No announcement yet.

Problems after Mess Under Intake...

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Problems after Mess Under Intake...

    [Also posted over at m42club -- hope that's OK]

    This past weekend I completed the "Mess under the intake" delete, but have ended up with worse idle and a "Check Engine" warning. Car is a 91 318i convertible with 142K miles. Very well maintained and ran perfectly, until the port on the top of the plastic coolant pipe snapped off. In an effort to make things simpler, I followed the many threads available here and on several other forums. I capped off the top port on a new coolant pipe, and the water outlet from the head. Deleted vacuum and water hoses under intake, leaving a vacuum line from the valve cover to the throttle body, and another from the ICV to the air inlet boot. The pictures in the following thread are exactly what I see (minus the clean engine):

    http://www.m42club.com/forums/showthread.php?t=3621

    I did leave the throttle body heater plate in place, simply because I did not have any cutting wheels for my dremel to shorten the studs: there is no water lines running to the heater plate. The plates ports are not capped off, since it appeared to be a closed system into itself.

    During the tear-down I cleaned out with intake manifolds and sprayed down the fuel injectors; I did not remove the injectors. I used two new gaskets for lower then upper manifolds, along with a new throttle body gasket.

    The vacuum hoses from valve cover and ICV do not appear to be collapsing and I've found no coolant leaks.

    The problems are rough coughing idle, an intermittent "Check Engine" light, and a high pitched whining sound from the top of the engine. The sound isn't quite a whistle, but is related to RPMs and very noticeable from inside the car. The idle smooths when revved high, and on a quick trip around the neighborhood the car ran decent. Pulling back into the driveway was loud and painful.

    My concerns are that I:

    • mucked up a fuel injector by just spraying it off externally
    • seated something incorrectly and created a leak somewhere on one of the manifolds
    • angered the Gods by working on the car on SuperBowl Sunday


    Any suggestions on correcting the issues? Anything jump out that I may have forgotten? Thanks for the help!


    John

    #2
    I suspect a vac leak.
    check with carb cleaner ( start engine, spray carb cleaner near all things you messed with , if speed , idle changes you found your vac leak.)


    check all your wiring, maybe you bumped something

    Idle control valve. did you take it off to do the work, did you check the hoses, might have looked good at time of removal, but if brittle might ave cracked on replacement.

    Comment


      #3
      Thanks 3b -- I'm hoping for a simple vacuum leak that I can chase down and fix. Any thoughts on the high pitched whine I heard?

      I did remove the ICV: reused the hose from cover to it, new from ICV outlet to intake elbow. I'll recheck all the hoses and connections. Planning to dive back into it this weekend...




      John

      Comment


        #4
        I would say you have a direct leak in the intake manifold somewhere. That "whistling" sound would be air rushing in from a small hole somewhere. I would recommend disassembling the manifold and checking the gaskets.
        sigpic

        Comment


          #5
          Thanks Massimo!
          I'm planning to go all the way back in, replace or realign the gaskets and check everything more thoroughly. May go ahead and pull the injectors for a proper cleaning -- opinions on cleaning vs. replacing with Mustang 4 pintle injectors?

          Comment


            #6
            Sorry for the delay -- here is a final update:

            As suggested above, it was a vacuum leak along the lower intake manifold. After tearing everything apart and being more diligent at proper re-assembly, the car now runs much better than before.

            Thanks to all for the help, and to the past posters who detailed the process so thoroughly.

            Comment

            Working...
            X